There is known a mineral-winning mining cutter-loader (see, for example, UK Application No. 2081778A, Int. Cl..sup.2 E21C 27/32) with a chainless feed system, comprising a housing and a gantry.
The housing is arranged at the working-face side of the conveyer and has its longitudinal axis extending along the conveyer. Accommodated along the longitudinal axis of the housing, in the cantilever fashion at the ends thereof are work-performing members for breaking the mineral and loading it onto the conveyer.
The housing accommodates therein the drive mechanisms of the work-performing members. Overlying the conveyer is a gantry pivotally connected with the housing.
The gantry accommodates the feed mechanism of the cutter-loader, including gears with horizontal axes of rotation, arranged at the working-face side of the conveyer, and a drive with reduction gearing to actuate the gears.
A guiding rack is mounted on the conveyer at the working-face side thereof, intended for meshing interaction with the gears as the cutter-loader is displaced along the working-face.
In this structure of the prior art the housing is mounted for vertical adjustment relative to the gantry.
The housing is provided with hydraulic supports bearing upon the floor of the seam, which are in the form of hydraulic cylinders. Arranged between the housing and the gantry are vertical hydraulic cylinders intended to perform vertical adjustment of the housing relative to the gantry as the thickness of the mineral seam varies.
The provision in the structure of the prior art for vertical adjustment of the housing alone relative to the gantry is insufficient for operation in thin seams, since under these conditions more often than not there arises the necessity of vertical adjustment, first and foremost, of the gantry itself. This adjustment could be required when, under the thin seam conditions, there arises the necessity of passing under the gantry oversize pieces of the mineral, or else of passing the gantry itself under a sagging beam of the roof support, and so on.
In the structure of the prior art, the vertical position of the gantry relative to the conveyer is practically inadjustable to avoid interference with the meshing of the gears of the feed mechanism with the rack attached to the conveyer.
The mineral-winning mining cutter-loader of the prior art is impractical for operation in thin seams, particularly those in the range of thicknesses from 0.65 to 1 meter, because the above described arrangement of the propulsion gears results in the gantry being of a relatively great height.